Hydroentangled nonwoven material

ABSTRACT

A hydroentangled nonwoven material ( 8 ), includes a mixture of randomized continuous filaments ( 3 ) and natural fibres ( 5 ), wherein at least part of the staple fibres and/or the continuous filaments includes thermoplastic material. The nonwoven material is bonded in a non-random bonding pattern including a plurality of bonding sites ( 14 ) in which thermoplastic material included in the nonwoven material has been caused to at least partly soften or melt to create thermal bonds between the continuous filaments. The nonwoven material includes no other thermal bonds between the filaments than provided by the non-random bonding pattern. The nonwoven material may also contain synthetic staple fibers ( 6 ).

TECHNICAL AREA

The present invention refers to a hydroentangled composite nonwovenmaterial, comprising a mixture of continuous filaments, synthetic staplefibres, and natural fibres.

BACKGROUND OF THE INVENTION

Absorbent nonwoven materials are often used for wiping spills andleakages of all kinds in industrial, service, office and home locations.The basic synthetic plastic components normally are hydrophobic and willabsorb oil, fat and grease, and also to some degree water by capillaryforce. To reach a higher water absorption level, cellulosic pulp isoften added. A variety of demands are put on nonwoven materials made forwiping purposes. An ideal wiper should be strong, absorbent, abrasionresistant and exhibit low linting. In order to replace textile wipers,which is still a major part of the market, the nonwoven wipers shouldfurther be soft and have a textile touch.

Nonwoven materials comprising mixtures of cellulosic pulp and syntheticfibres can be produced by conventional papermaking processes, see e.g.U.S. Pat. No. 4,822,452, which describes a fibrous web formed bywetlaying, the web comprising staple length natural or synthetic fibresand cellulose paper-making fibres. An associative thickener is furtheradded to the furnish.

Hydroentangling or spunlacing is a technique introduced during the1970'ies, see e g CA patent no. 841 938. The method involves forming afibre web which is either drylaid or wetlaid, after which the fibres areentangled by means of very fine water jets under high pressure. Severalrows of water jets are directed against the fibre web which is supportedby a movable fabric. The entangled fibre web is then dried. The fibresthat are used in the material can be synthetic or regenerated staplefibres, e g polyester, polyamide, polypropylene, rayon or the like, pulpfibres or mixtures of pulp fibres and staple fibres. Spunlace materialscan be produced in high quality to a reasonable cost and have a highabsorption capacity. They can e g be used as wiping material forhousehold or industrial use, as disposable materials in medical care andhygiene articles etc.

In WO 96/02701 there is disclosed hydroentangling of a foamformedfibrous web. Foamforming is a special variant of wetlaying where thewater besides fibres and chemicals also contains a surfactant whichmakes it possible to create foam where the fibres can be enmeshed in andbetween the foam bubbles. The fibres included in the fibrous web can bepulp fibres and other natural fibres and synthetic fibres.

Through e g EP-B-0 333 211 and EP-B-0 333 228 it is known tohydroentangle a fibre mixture in which one of the fibre components ismeltblown fibres. A web of meltblown fibres is combined with anotherfibrous web and the combined webs are hydroentangled, or alternatively a“coform material” comprising an essentially homogeneous mixture ofmeltblown fibres and other fibres is airlaid on a forming fabric andsubsequently hydroentangled.

Through EP-A-0 308 320 it is known to bring together a prebonded web ofcontinuous filaments with a separately prebonded wetlaid fibrousmaterial containing pulp fibres and staple fibres and hydroentangletogether the separately formed fibrous webs to a laminate. In such amaterial the fibres of the different fibrous webs will not be integratedwith each other since the fibres already prior to the hydroentanglingare bonded to each other and only have a very limited mobility. Thematerial will show a marked two-sidedness. The staple fibres used have apreferred length of 12 to 19 mm, but could be in the range from 9.5 mmto 51 mm.

EP-A-0 492 554 describes a nonwoven material made from continuousfilaments and pulp fibers. Pulp fibers are wet laid on top of a bondedspunlaid web and the two layers are combined by hydroentanglement. As inthe above case it is difficult to integrate a prebonded web of filamentswith other fibers and the hydroentanglement energy required to combinethe pulp fibers with the bonded spunlaid web is rather high.

WO 2005/042819 discloses a hydroentangled, well integrated compositenonwoven material, comprising a mixture of continuous filaments,synthetic staple fibres, and natural fibres, said material having areduced two-sidedness. The synthetic staple fibres are short, having alength between 3 and 7 mm. The choice of such short staple fibresenables pulp fibres and staple fibres to be better mixed and distributedthoroughly throughout the nonwoven material. There are no thermal bondsbetween the filaments to ascertain that the fibres and filaments arefully mixed with each other.

WO 02/38846 discloses a hydroentangled nonwoven composite structurecontaining recycled synthetic fibrous material and continuous filaments.The recycled synthetic fibrous material comprises short thread elements,which are fractions of fibrous material separated from a bonded materialsuspended in a liquid. The continuous filaments are supplied in the formof a web, which is handled in roll form and therefore has to be bondedat least to some extent. The hydroentangled material is dried utilizinga non-compressive drying process such as through-air drying.

One problem occurring in many webs containing long filaments is thatafter use as a wiper for some time, segments of the filaments may comeloose and rise as loops above the surface of the web material. Thisphenomenon is referred to as “pilling”. This may especially be a problemin web materials comprising a mixture of filaments and short fibers(shorter than about 8 mm) since these short fibers have a very limitedability to twist around and entangle with the filaments. The problemwith pilling may be reduced by increasing the hydroentanglement energy,which however is disadvantageous in other aspects.

OBJECT AND MOST IMPORTANT FEATURES OF THE INVENTION

It is an object of the present invention to provide an improvedhydroentangled well integrated composite nonwoven material, comprising amixture of continuous filaments and natural fibres and which is abrasionresistant and less sensitive to pilling and which may be produced withan energy effective process.

This has according to the invention been obtained by a hydroentangledcomposite nonwoven material, comprising a mixture of randomizedcontinuous filaments and natural fibres, in which the nonwoven materialis bonded in a non-random bonding pattern comprising a plurality ofbonding sites, in which thermoplastic material comprised in the nonwovenmaterial has been caused to at least partly soften or melt to createthermal bonds between the continuous filaments and wherein the nonwovenmaterial comprises no other thermal bonds between the filaments thanprovided by said non-random bonding pattern.

In one aspect of the invention the bonding pattern comprises a pluralityof bonding sites, each having a bonding area of 0.1 to 3 mm², preferablyfrom 0.15 to 2 mm².

In a further aspect of the invention the bonding pattern has a bondingdensity of between 1 and 100 bonding sites per cm², preferably between 2and 90 bonding sites per cm² and more preferably between 5 and 80bonding sites per cm².

In a still further aspect of the invention the bonding sites cover anarea of between 1 and 25%, preferably between 2 and 20% and morepreferably between 5 and 18% of the thermally bonded nonwoven material.

According to one embodiment the nonwoven material further comprisessynthetic staple fibres. Said synthetic staple fibers preferably have alength of 3 to 7 mm, and more preferably 4 to 6 mm.

According to a further embodiment no more than 10% of the syntheticstaple fibers contained in the nonwoven material has a length greaterthan greater than 7 mm and preferably it is free from staple fibershaving a length greater than 7 mm.

According to one embodiment the material according to the inventioncomprises a mixture of 10-50% continuous filaments, 5-50% syntheticstaple fibres, and 20-85% natural fibres, all percentages calculated byweight of the total nonwoven material. A more preferred material has15-35% continuous filaments. More preferred is also 5-25% syntheticstaple fibres. Also more preferred is 40-75% natural fibres.

In a further embodiment the continuous filaments are spunlaid filaments.

The continuous filaments may be chosen from the group: polypropylene,polyesters and polylactides.

According to a further embodiment the synthetic staple fibres are chosenfrom the group: polyethylene, polypropylene, polyesters, polyamides,polylactides, rayon, and lyocell.

In one aspect of the invention at least a part of the synthetic staplefibres are bicomponent fibers having a low melting component and a highmelting component, wherein said thermobonding is accomplished by meltingof the low melting component of the bicomponent fibres to create saidbonding sites between the continuous filaments.

A preferred material according to the invention is where the naturalfibres consist of pulp fibres, more preferably wood pulp fibres.

A further object of the invention is to provide a method of producing animproved hydroentangled well integrated composite nonwoven material,comprising a mixture of continuous filaments and natural fibres which isabrasion resistant and less sensitive to pilling and which may beproduced with an energy effective process.

This has according to the invention been obtained by providing a methodcomprising forming a web of continuous filaments on a forming fabric,wherein said web of continuous filaments is unbonded with no thermalbondings between the filaments, and applying a wet-formed fibredispersion containing natural fibres on top of said unbonded web ofcontinuous filaments, thus forming a fibrous web containing saidcontinuous filaments and natural fibres, hydroentangling the fibrous webto form a nonwoven material, and subsequently thermobonding thehydroentangled nonwoven material in a non-random bonding patterncomprising a plurality of bonding sites in which thermoplastic materialcomprised in the nonwoven material is caused to at least partly softenor melt to create thermal bonding sites between the continuousfilaments.

In one aspect of the invention the thermobonding is accomplished by aprocess chosen from: heat bonding, ultrasonic bonding, laser bonding.

In one embodiment the wet-formed fibre dispersion also containssynthetic staple fibers. The synthetic staple fibers preferably have alength of 3 to 7 mm, preferably 4 to 6 mm.

In a further aspect of the invention at least part of the staple fiberscomprised in the fibrous web that is hydroentangled, are bicomponentfibers having a low melting component and a high melting component,wherein said thermobonding is accomplished by melting of the low meltingcomponent of the bicomponent fibres to create said bonding sites betweenthe continuous filaments.

DESCRIPTION OF THE DRAWINGS

The invention will be closer described below with reference to someembodiments shown in the accompanying drawings.

FIG. 1 shows schematically an exemplary embodiment of a device forproducing a hydroentangled nonwoven material according to the invention.

FIGS. 2 and 3 show ESEM pictures in different magnifications of athermobonded hydroentangled nonwoven according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The improved hydroentangled well integrated composite nonwoven materialcomprises a mixture of continuous filaments, synthetic staple fibres,and natural fibres. These different types of fibres are defined asfollows.

Filaments

Filaments are fibres that in proportion to their diameter are very long,in principle endless. They can be produced by melting and extruding athermoplastic polymer through fine nozzles, whereafter the polymer willbe cooled, preferably by the action of an air flow blown at and alongthe polymer streams, and solidified into strands that can be treated bydrawing, stretching or crimping. Chemicals for additional functions canbe added to the surface.

Filaments can also be produced by chemical reaction of a solution offibre-forming reactants entering a reagent medium, e. g. by spinning ofviscose fibres from a cellulose xanthate solution into sulphuric acid.

Meltblown filaments are produced by extruding molten thermoplasticpolymer through fine nozzles in very fine streams and directingconverging air flows towards the polymers streams so that they are drawnout into continuous filaments with a very small diameter. Production ofmeltblown is described in e.g. U.S. Pat. Nos. 3,849,241 and 4,048,364.The fibres can be microfibres or macrofibres depending on theirdimensions. Microfibres have a diameter of up to 20 μm, usually 2-12 μm.Macrofibres have a diameter of over 20 μm, usually 20-100 μm.

Spunbond filaments are produced in a similar way, but the air flows arecooler and the stretching of the filaments is done by air to get anappropriate diameter. The fibre diameter is usually above 10 μm, usually10-100 μm. Production of spunbond is e. g. described in U.S. Pat. No.4,813,864 or 5,545,371.

Spunbond and meltblown filaments are as a group called spunlaidfilaments, meaning that they are directly, in situ, laid down on amoving surface to form a web, which further on in the process is bonded.Controlling the ‘melt flow index’ by choice of polymers and temperatureprofile is an essential part of controlling the extruding and therebythe filament formation. The spunbond filaments normally are stronger andmore even than meltblown filaments.

Tow is another source of filaments, which normally is a precursor in theproduction of staple fibres, but also is sold and used as a product ofits own. In the same way as with spunlaid fibres, fine polymer streamsare drawn out and stretched, but instead of being laid down on a movingsurface to form a web, they are kept in a bundle to finalize drawing andstretching. When staple fibres are produced, this bundle of filaments isthen treated with spin finish chemicals, normally crimped and then fedinto a cutting stage where a wheel with knives will cut the filamentsinto distinct fibre lengths that are packed into bales to be shipped andused as staple fibres. When tow is produced, the filament bundles arepacked, with or without spin finish chemicals, into bales or boxes.

Any thermoplastic polymer having sufficient coherent properties to letitself be drawn out in this way in the molten state, can in principle beused for producing meltblown or spunbond fibres. Examples of usefulpolymers are polyolefins, such as polyethylene and polypropylene,polyamides, polyesters and polylactides. Copolymers of these polymersmay of course also be used, as well as natural polymers withthermoplastic properties. Bicomponent filaments may also be used.Bicomponent fibers and filaments refer to fibers and filaments havingtwo polymeric compounds arranged in a core-sheath (concentric oreccentric), a side by side, a matrix or “island in sea” configuration,chosen to ensure that one component softens at a sufficiently lowertemperature than the other component, in order to maintain a structuralintegrity of the fiber or filament.

Natural Fibres

There are many types of natural fibres that can be used, especiallythose that have a capacity to absorb water and tendency to help increating a coherent sheet. Among the natural fibres possible to usethere are primarily cellulosic fibres, such as seed hair fibres, e. g.cotton, kapok, and milkweed; leaf fibres e. g. sisal, abaca, pineapple,and New Zealand hamp; or bast fibres e. g. flax, hemp, jute, kenaf, andpulp. Wood pulp fibres are especially well suited to use, and bothsoftwood fibres and hardwood fibres are suitable, as well as recycledfibres. The pulp fibre length will vary from around 3 mm for softwoodfibres and around 1.2 mm for hardwood fibres and a mix of these lengths,and even shorter, for recycled fibres.

Staple Fibres

The staple fibres used can be produced from the same polymers as thefilaments discussed above. Bicomponent staple fibers may also be used.Other usable staple fibres are those made from regenerated cellulosesuch as viscose and lyocell. They may be treated with spin finish andcrimped, but this is not necessary for the type of processes preferablyused to produce the material described in the present invention.

Spin finish and crimp is normally added to ease the handling of thefibres in a dry process, e. g. a carding equipment, and/or to givecertain properties, e.g. hydrophilicity, to a material consisting onlyof these fibres, e.g. a nonwoven topsheet for a diaper.

The cutting of the fibre bundle normally is done to result in a singlecut length, which can be altered by varying the distances between theknives of the cutting wheel. Depending on the planned use differentfibre lengths are used, between 25-50 mm for a thermobonded nonwoven.Wetlaid hydroentangled nonwoven materials normally use fibre lengthsbetween 12 and 18 mm, or down to 9 mm. Fibre lengths between 3 and 7 mmare disclosed in WO 2005/042819.

For hydroentangled materials made by traditional wetlaid technology, thestrength of the material and its properties like surface abrasionresistance are increased as a function of the fibre length (for the samethickness and polymer of the fibre).

When continuous filaments are used together with staple fibres and pulp,the strength of the material will mostly come from the filaments.

Process

One general example of a method for producing the material according tothe present invention is shown in FIG. 1. Continuous filaments 2 arelaid down on an endless forming fabric 1 in a manner described ingreater detail below. Excess air is sucked off through the formingfabric 1, to form the precursor of a web 3. The forming fabric 1 withthe continuous filaments is advanced to a wetlaying station, where aslurry comprising a mixture of natural fibres 5 and staple fibres 6 iswetlaid via a headbox 4 on and partly into the precursor web ofcontinuous filaments 2. Excess water is drained through the formingfabric.

In an alternative embodiment bicomponent staple fibers 11 having alength of 10 to 30 mm are laid as a thin layer on the forming fabric 1prior to the continuous filaments. The bicomponent staple fibers arepreferably drylaid on the forming fabric 1.

The forming fabric 1 with the filaments and fibre mixture is advanced toa hydroentangling station 7, where the filaments and fibres are mixedintimately together and bonded into a nonwoven web 8 by the action of aplurality of thin jets of high-pressure water impinging on the filamentsand fibres to mix and entangle them with each other. Entangling water isdrained through the forming fabric. The forming fabric 1 is advanced toa drying station 12, e.g. by blowing hot air onto and through thehydroentangled nonwoven web 8 to dry the web.

Subsequently the nonwoven web is thermobonded in a thermobonding station13 in a bonding pattern, which will be described in greater detailbelow. The nonwoven web is then wound up and converted to a suitableformat and packed.

Filament ‘Web’

According to the embodiment shown in FIG. 1 the continuous filaments 2made from extruded molten thermoplastic pellets are laid down directlyon the forming fabric 1 where they are allowed to form an unbonded webstructure 3 in which the filaments can move relatively freely from eachother. This is achieved preferably by making the distance between thenozzles and the forming fabric 1 relatively large, so that the filamentsare allowed to cool down before they land on the forming fabric to reacha lower temperature at which their stickiness is largely reduced.Alternatively cooling of the filaments before they are laid down on theforming fabric is achieved in some other way, e.g. by means of usingmultiple air sources using air 10 is used to cool the filaments whenthey have been drawn out or stretched to the preferred degree. The airused for cooling, drawing and stretching the filaments is sucked throughthe forming fabric, to let the filaments follow the air flow into themeshes of the forming fabric to be stayed there. A good vacuum might beneeded to suck off the air.

The speed of the filaments as they are laid down on the forming fabricis much higher than the speed of the forming fabric, so the filamentswill form irregular loops and bends as they are collected on the formingfabric to form a very randomized precursor web.

The basis weight of the formed filament precursor web 3 should bebetween 2 and 50 g/m².

Wet-Laying

The pulp 5 and staple fibres 6 are slurried in a conventional way,either mixed together or first separately slurried and then mixed, andconventional papermaking additives such as wet and/or dry strengthagents, retention aids, dispersing agents, are added, to produce a wellmixed slurry of pulp and staple fibres in water. In an alternativeembodiment a surfactant is added to produce a foam of the slurry, sothat the slurry will be foam formed, which is a variant of wet-laying.

This mixture is pumped out through a wet-laying headbox 4 onto themoving forming fabric 1 where it is laid down on the unbonded precursorfilament web 3 with its freely moving filaments. The pulp and the staplefibres will stay on the forming fabric and the filaments. Some of thefibres will enter between the filaments, but the vast majority of themwill stay on top of the filament web.

The excess water is sucked through the web of filaments laid on theforming fabric and down through the forming fabric, by means of suctionboxes arranged under the forming fabric.

Hydroentangling

The fibrous web of continuous filaments and staple fibres and pulp ishydroentangled while it is still supported by the forming fabric 1 andis intensely mixed and bonded into a composite nonwoven material 8. Aninstructive description of the hydroentangling process is given in CApatent no. 841 938.

In the hydroentangling stage 7 the different fibre types will beentangled and a composite nonwoven material 8 is obtained in which allfibre types are substantially homogeneously mixed and integrated witheach other. The fine mobile spunlaid filaments are twisted around andentangled with themselves and the other fibres which gives a materialwith a very high strength. The energy supply needed for thehydroentangling is relatively low, i.e. the material is easy toentangle. The energy supply at the hydroentangling is appropriately inthe interval 50-500 kWh/ton.

No bonding, e. g. thermal bonding or hydroentangling, of the precursorfilament web 3 should occur before the pulp 5 and staple fibres 6 arelaid down 4. The filaments should be free to move in respect of eachother to enable the staple and pulp fibres to mix and twirl into thefilament web during entangling. Thermal bonding points between filamentsin the filament web at this part of the process would act as blockingsto stop the staple and pulp fibres to enmesh near these bonding points,as they would keep the filaments immobile in the vicinity of the thermalbonding points. The ‘sieve effect’ of the web would be enhanced and amore two-sided material would be the result. By no thermal bondings wemean that there are substantially no points where the filaments havebeen exerted to heat and pressure, e. g. between heated rollers, torender some of the filaments pressed together such that they will besoftened and/or melted together to deform in points of contact. Somebond points could especially for meltblown result from residualtackiness at the moment of laying-down, but these will be withoutdeformation in the points of contact, and would probably be so weak asto break up under the influence of the force from the hydroentanglingwater jets.

The strength of a hydroentangled material based on only staple and pulpwill depend heavily on the amount of entangling points for each fibre;thus long staple fibres, and long pulp fibres, are preferred. Whenfilaments are used, the strength will be based mostly on the filaments,and reached fairly quickly in the entangling. Thus most of theentangling energy will be spent on mixing filaments and fibres to reacha good integration. The unbonded open structure of the filamentsaccording to the invention will greatly enhance the ease of this mixing.

The pulp fibres 5 are irregular, flat, twisted and curly and getspliable when wet. These properties will let them fairly easily be mixedand entangled into and also stuck in a web of filaments, and/or longerstaple fibres. Thus pulp can be used with a filament web that isprebonded, even a prebonded web that can be treated as a normal web byrolling and unrolling operations, even if it still does not have thefinal strength to its use as a wiping material.

The polymer fibres 6, though, are mostly round, even, of constantdiameter and slippery, and are not effected by water. This makes themharder to entangle and force down into a prebonded filament web, theywill tend to stay on top. Staple fibers of varying lengths may be used,from 3 mm up to about 18 mm. According to one embodiment of theinvention short staple fibers, from 3 to 7 mm, more preferably from 4 to6 mm, are used.

The entangling stage 7 can include several transverse bars with rows ofnozzles from which very fine water jets under very high pressure aredirected against the fibrous web to provide an entangling of the fibres.The water jet pressure can then be adapted to have a certain pressureprofile with different pressures in the different rows of nozzles.

Alternatively, the fibrous web can before hydroentangling be transferredto a second entangling fabric. In this case the web can also prior tothe transfer be hydroentangled by a first hydroentangling station withone or more bars with rows of nozzles.

Drying

The hydroentangled wet web 8 is then dried, which can be done onconventional web drying equipment, preferably of the types used fortissue, such as through-air drying 12 or heated can drying.

Thermobonding

If the short staple fibers 6 and natural fibers 5 are not sufficientlyintegrated with the continuous filaments 2 there will be a side withrelatively high amount of filaments which are not anchored by the shortfibers and the material will be sensitive to abrasion and pilling willoccur when the material is used for wiping. Long segments of thefilaments come loose and rise above the surface of the material. Even ifthe continuous filaments are well integrated with the short fiberspilling may be a problem, especially since short fibers of up to 7 mm inlength have a very limited ability to twist around and entangle with thefilaments as compared to longer staple fibers.

In order to reduce the problem of pilling the hydroentangled and driedweb 8 is according to the invention thermobonded 13 in a non-randombonding pattern comprising a plurality of bonding sites 14, in which thethermoplastic material of the continuous filaments 2 and/or thesynthetic staple fibers 6 has been caused to at least partly soften ormelt to create thermal bonds between the continuous filaments. Thethermobonding may either take place in-line with the hydroentangling anddrying process before winding the web material 8 into mother rolls, orin a subsequent process for example in connection with converting thematerial into suitable formats.

Thermobonding may take place by any suitable process such as heatbonding, ultrasonic bonding or laser bonding. Heat bonding may be in theform of hot calendering. The bonding pattern should comprise a pluralityof discrete relatively small bonding sites adapted to create bondsbetween the filaments preventing or at least considerably reducing therisk for segments of filaments to come loose and rise from the surfaceof the material to cause pilling. The bonding sites 14 could have anygeometrical shape and suitably each have a bonding area of 0.1 to 3 mm²,preferably from 0.15 to 2 mm².

The bonding density, i.e. the number of bonding sites 14 per surfacearea, is a further important aspect, and suitably the bonding density isbetween 1 and 100 bonding sites per cm², preferably between 2 and 90bonding sites per cm² and more preferably between 5 and 80 bonding sitesper cm². The bonding sites are preferably uniformly distributed over theweb material 8, but may also be arranged in groups. In the latter casethe number of bonding sites is taken as an average value over a surfacearea that is large enough to be representative for the bonding patternin question.

The total bonding area, which is defined as the surface area of thethermally bonded web material 8 that is occupied by bonding sites inrelation to the entire area circumscribed by the bonding patternincluding the non-bonded areas between bonding sites, is suitablybetween 1 and 25%, preferably between 2 and 20% and more preferablybetween 5 and 18%.

The thermobonding needs only be sufficient for softening or melting thesurface layer of the filament side of the nonwoven material 8, which isthe fabric side of the web onto which the continuous filaments 2 havebeen laid and which usually has a higher amount of filaments than theother side, even in cases where a good integration between short fibersand filaments has been achieved. This may be accomplished for example byapplying only a very slight pressure by a patterned heated roll 15against the side of the nonwoven material 8 to be thermobonded andhaving a non-heated counter roll 16. Normally both the pattern roll 15and the counter roll 16 are however heated, while the pattern roll hasthe highest temperature, so that there is a temperature differencebetween the two rolls.

In one embodiment described above bicomponent staple fibers are laid onthe forming fabric as a first layer, while the filaments 2 are laid ontop of the bicomponent fiber layer 11. The mixture of natural fibers 5and short staple fibers 6 are then wetlaid on top of the filaments inthe same manner as the other embodiments. During hydroentangling thebicomponent fibers 11 will migrate with the filaments, but will mainlyremain close to the fabric-side of the web. Thermobonding from thefabric side of the web will cause the low temperature softeningcomponent of the bicomponent fibers 11 to soften and to createthermobonds between the filaments, while the rest of the web is not orat least less effected by the thermobonding. Thus the thermal bonds areonly created where most needed.

If the nonwoven material 8 is thermobonded to a very high degree thiswill negatively influence other properties such as absorption andstiffness for example.

Further Process Steps and Treatments

The nonwoven material is then converted in known ways to suitableformats and packed. The structure of the nonwoven material can bechanged by further processing such as microcreping, embossing, etc. Tothe nonwoven material can also be added different additives such as wetstrength agents, binder chemicals, latexes, debonders, etc.

Nonwoven Material

Nonwoven materials according to the invention can be produced with awide range of basis weights, preferably with a basis weight of 20-120g/m², more preferably 50-80 g/m².

The nonwoven materials may comprise only continuous filaments andnatural fibers, but may in addition also contain staple fibres. Thestaple fibers may be based on different polymers, with different lengthsand dtex. According to one embodiment the staple fibers are relativelyshort, between 3 and 7 mm, since these are more easily mixed andintegrated with the natural fibers and the filament. It is alsocontemplated to add a certain proportion of synthetic staple fibreslonger than 7 mm and even longer than 12 mm to the composite nonwoven.This certain proportion could be up to 10% of the total amount ofsynthetic staple fibres, based on weight portions.

The invention is of course not limited to the embodiments shown in thedrawings and described above and in the examples but can be furthermodified within the scope of the claims.

EXAMPLES

A number of hydroentangled materials according to the invention withdifferent bonding patterns were produced and tested with respect tointeresting parameters in comparison with reference materials which werenot thermobonded.

Specific Tests Used:

Taber wet—A wet (soaked in water and drip dried for 1 minute) materialto be tested is fastened on a plate and abrasive wheels are made to runin a circle upon it, according to ASTM D 3884-92, with somemodifications caused by measuring a thin, non-permanent material, andnot floor carpets as the method was originally designed for. Themodifications consist of using wheels Calibrase CS-10, but with no extraweights added, and only 100 and 150 revolutions are made. The resultingabrasion wear is compared to an internal standard, where 1 means‘abraded to shreds’ and 5 means ‘hardly visibly affected’. The apparatusused was of the type ‘5151 Abraser’ from Taber Industries, N. Tonawanda,N.Y., USA.

The materials were tested in a wet condition in order to simulate theintended use, and since wet materials are more sensitive to pilling andtherefore give a clearer result. The test was made on nonwoven samplesaccording to the invention and on reference samples, where the two sidesof the samples are designated fabric side, meaning the side of thenonwoven which has been against the forming fabric when the filaments,staple fibres and pulp have been laid down, and the free side, meaningthe side of the nonwoven from which the different fibres have been laiddown.

Example 1

A 0.4 m wide web of spunlaid filaments was laid down onto a formingfabric at 20 m/min such that the filaments were not bonded to eachother. By a 0.4 m wide headbox a fibre dispersion containing pulp fibresand shortcut staple fibres was laid onto the unbonded web of spunlaidfilaments and the excess water was drained and sucked off.

The unbonded spunlaid filaments and wetlaid fibres were then mixed andbonded together by hydroentanglement. The hydroentanglement was donefrom the free side and the pulp and staple fibres were thus moved intoand mixed intensively with the spunlaid filament web. The hydroentangledmaterial was dewatered and then dried using a through-air drum drier.Finally the material was thermobonded from the fabric side using a hotcalendaring technique (Hot S-Roll Technology by Andritz Küsters GmbH &Co. KG, Germany) and using different bonding patterns with differentbonding densities and bonding areas.

The total basis weight of the tested filament-staple-pulp composites wasaround 80 and 65 gsm respectively. The composition of the 80 gsmcomposite material was: 25% spunlaid polypropylene filaments having afineness of 2.4 dtex, 10% shortcut polypropylene staple fibres having alength of 6 mm and a fineness of 1.7 dtex and 65% chemical pulp. Theamounts are given as wt % based on the dry weight of the fibres. Thecomposition of the 65 gsm composite materials was: 25% spunlaidpolypropylene filaments having a fineness of 4 dtex, 10% shortcutpolypropylene staple fibres having a length of 6 mm and a fineness of1.7 dtex and 65% chemical pulp. A wet strength agent in the form PAE wasadded. The amount in both cases was 0.2 wt % active substance PAEcalculated on the dry weight of the composite material. The 80 gsmmaterial was hydroentangled with a total entanglement energy of 200kWh/ton and the 65 gsm material was hydroentangled with a totalentanglement energy of 250 kWh/ton.

The surface abrasion wear resistance strength measured by the Taberabrasion wear test on the fabric side of the material, see Table 1. Ascan be seen the abrasion resistance was considerably improved by thethermobonding.

TABLE 1 Abrasion Abrasion Bonded Bonding Area of Line Temp. Temp. Lineresistance resistance area density bonding pressure embossing backingspeed 100 cycles 150 cycles Pattern (%) (no./cm2) sites (mm²) (N/mm)roll (° C.) roll (° C.) (m/min) (Scale) (Scale)  1* — — — — — — — 1 1 213 76 0.176 30 155 120 25 5 4 3 13 76 0.176 50 155 120 25 4 4 4 10 14.80.64 30 155 120 25 4 4  5** — — — — — — — 1 1 6 17 11 1.44 40 155 120 253 3 7 6.5 9 0.72 40 155 120 25 3 3 *= Ref. 80 gsm (withoutthermobonding) **= Ref. 65 gsm (without thermobonding)

1.-26. (canceled)
 27. A hydroentangled composite nonwoven material,comprising a mixture of randomized spunlaid filaments and wood pulpfibres, wherein one of the sides of the nonwoven material contains arelatively higher amount of spunlaid filaments than the opposite side ofthe nonwoven material, the nonwoven material is bonded in a non-randombonding pattern comprising a plurality of bonding sites each having abonding area of 0.1 to 3 mm², in which thermoplastic material comprisedin the nonwoven material has been caused to at least partly soften ormelt to create thermal bonds between the spunlaid filaments, and thethermal bonds do not penetrate the entire thickness of the material andare applied on the side containing the relatively higher amount ofspunlaid filaments, and wherein the nonwoven material comprises no otherthermal bonds between the filaments than provided by said non-randombonding pattern.
 28. The hydroentangled nonwoven material according toclaim 27, wherein the bonding sites cover an area of 1 and 25% of thetotal area of the thermally bonded nonwoven material.
 29. Thehydroentangled nonwoven material according to claim 27, wherein thebonding pattern has a bonding density of from 1 and 100 bonding sitesper cm².
 30. The hydroentangled nonwoven material according to claim 27,wherein further comprising synthetic staple fibers.
 31. Thehydroentangled nonwoven material according to claim 30, wherein thesynthetic staple fibers have a length of 3 to 7 mm.
 32. Thehydroentangled nonwoven material according to claim 31, wherein no morethan 10% of the synthetic staple fibers contained in the nonwovenmaterial has a length greater than greater than 7 mm.
 33. Thehydroentangled nonwoven material according to claim 27, wherein themixture is made up of 10-50% spunlaid filaments, 20-85% wood pulpfibres, and 5-50% synthetic staple fibres, all percentages calculated byweight of the total nonwoven material.
 34. The hydroentangled nonwovenmaterial according to claim 30, wherein at least part of the syntheticstaple fibers are bicomponent fibers having a low melting component anda high melting component, and the thermobonding is accomplished bymelting of the low melting component of the bicomponent fibres to createthe bonding sites between the spunlaid filaments.
 35. The hydroentanglednonwoven material according to claim 34, wherein the bicomponent staplefibers are predominantly located on one side of the nonwoven material,said one side also containing a relatively higher amount of spunlaidfilaments than the opposite side of the nonwoven material.
 36. A methodof producing a nonwoven material, comprising forming a web of spunlaidfilaments on a forming fabric, wherein said web of spunlaid filaments isunbonded with no thermal bondings between the filaments, and applying awet-formed fibre dispersion containing wood pulp fibres on top of saidunbonded web of spunlaid filaments, thus forming a fibrous webcontaining said spunlaid filaments and wood pulp fibres, andsubsequently hydroentangling the fibrous web to form a hydroentanglednonwoven material, thermobonding the hydroentangled nonwoven materialfrom the fabric side on which the spunlaid filaments are laid in anon-random bonding pattern comprising a plurality of bonding sites, eachhaving a bonding area of 0.1 to 3 mm² in which thermoplastic materialcomprised in the nonwoven material is caused to at least partly softenor melt to create thermal bonds between the spunlaid filaments, whereinonly a slight pressure is used at the thermobonding so as to soften ormelt only the spunlaid filaments and/or synthetic staple fibers locatedon and adjacent the fabric side of the nonwoven material.
 37. The methodas claimed in claim 36, wherein the thermobonding is accomplished by aprocess selected from: heat bonding, ultrasonic bonding, and laserbonding.
 38. The method as claimed in claim 36, wherein thehydroentangled nonwoven material is thermobonded in a bonding patterncomprising a plurality of bonding sites covering an area of 1 and 25% ofthe total area of the thermally bonded nonwoven material.
 39. The methodas claimed in claim 36, wherein the hydroentangled nonwoven material isthermobonded in a bonding pattern having a bonding density of from 1 and100 bonding sites per cm².
 40. A method as claimed in claim 36, whereinthe wet-formed fibre dispersion also contains synthetic staple fibers.41. The method as claimed in claim 40, wherein the synthetic staplefibres have a length of 3 to 7 mm.
 42. The method as claimed in claim40, wherein at least part of the staple fibers comprised in the fibrousweb that is hydroentangled, are bicomponent fibers having a low meltingcomponent and a high melting component, and said thermobonding isaccomplished by melting of the low melting component of the bicomponentfibres to create said bonds between the spunlaid filaments.
 43. A methodas claimed in claim 42, wherein a layer of bicomponent fibers is laid onthe forming fabric prior to laying the spunlaid filaments.
 44. Thehydroentangled nonwoven material according to claim 27, wherein thebonding sites cover an area of 2-20% of the total area of the thermallybonded nonwoven material, and the bonding pattern has a bonding densityof from 2 to 90 bonding sites per cm².
 45. The hydroentangled nonwovenmaterial according to claim 27, wherein the bonding sites cover an areaof 5-18% of the total area of the thermally bonded nonwoven material,and the bonding pattern has a bonding density of from 5 to 80 bondingsites per cm².
 46. The hydroentangled nonwoven material according toclaim 31, wherein the hydroentangled nonwoven material is free fromstaple fibers having a length greater than 7 mm.